Will 'Avengers: Endgame' Travel to New Dimensions?

The Quantum Realm has been established as a big deal in the Marvel Cinematic Universe, and perhaps it's more than about making things small or even traveling through time.

Much has been made of the importance of the Quantum Realm to the Marvel Cinematic Universe by filmmakers in the past couple of years, with Marvel Studios president Kevin Feige most recently underscoring how big a deal it will be going forward while promoting Captain Marvel. In the Marvel movies to date, however, the Quantum Realm has been confined mostly to the Ant-Man movies, which raises the question: What is so important about the Quantum Realm?

The majority of current fan speculation regarding the Quantum Realm follows the theory that it could allow people to travel through time. There is some small evidence for this, both stemming from 2018's Ant-Man and the Wasp, albeit indirectly: Scott Lang surviving Thanos' snap could be possible if he was technically outside time when it happened — of course, he could also simply be one of the 50 percent of humanity that survived — while Janet Van Dyne's survival for a long period of time without any obvious source of food or water would suggest that something odd is happening there that might indicate time doesn't work as it should.

However, there's another potential explanation for both events: The Quantum Realm isn't actually a realm as such things are traditionally thought of — instead, it's a gateway to multiple other realms, or realities. That would explain both Scott's survival (He was outside of the regular MCU when it happened) and Janet's healthiness, as well; she didn't stay in the Quantum Realm for the entire time she was missing, and found sustenance elsewhere.

This second possibility presents a whole new path that Avengers: Endgame could take in resolving the threat of Thanos. After all, if the Avengers have the ability to travel to parallel realities — something that could explain leaked photos from the set of Endgame that show the characters in familiar, if unlikely, settings — then it's very possible that they could recruit parallel Avengers to form a superhero army or, more excitingly, find and use parallel reality versions of the Infinity Stones to confront Thanos on an even playing field.

This isn't an idea that's entirely new. The recently completed Infinity Wars comic book series featured the question of using one universe's Infinity Stones in another universe, as heroes crossed realities in an attempt to find a way to deal with a villain wielding seemingly ultimate power. They didn't, much to Loki's distress — he was one of the good guys, this time out — but just as some details and story mechanics change between comics and movies, so it is possible that the answer would be very different on the big screen — especially if it means that the threat of Thanos can be ended once and for all at the end of Endgame.

Such a plot mechanism would also offer both upbeat closure for whichever characters leave the MCU with Endgame — imagine the possibility for Steve Rogers to go to a reality where Peggy Carter is still around — and endless possibility for the future of the MCU, with multiple realities ready to be explored. In that alone, the teases about the importance of the Quantum Realm would be earned.

It's still a couple of months before Avengers: Endgame hits theaters, and speculation about how the storyline will resolve, and just what part the Quantum Realm will play in its conclusion, will doubtlessly only grow during that time. Perhaps there's an alternate reality wherein everyone already knows how it ends and rests easy knowing that alternate realities discovered via the Quantum Realm played a big part.